Problems with sound

I have a Nokia-6 TA-1021. After upgrading to Android 8.0.0 speakers, no matter what is reproduced through them (music, game or movies) -

sizzle and fade, the sound became terrible. This is especially audible when you apply the speaker to your ear at a minimum volume level. This is unacceptable, especially for Nokia. What to do? How to solve this problem or how to return to the previous version of Android.